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Automation Keeps Fab Shop Humming After Hours

By: Brad Kuvin

Thursday, October 01, 2009
 
American Metal Fab, Inc., in the
Automated material loand and unload equipment on three of its six CNC turret presses
Automated material load and unload equipment on three of its six CNC turret presses allow American Metal Fab to run lights out over an unmanned second shift to
provide enough parts for downstream operations.
small southwestern-Michigan town of Three Rivers, is enduring the same unprecedented challenges faced by most if not all metalforming companies. Yet it appears prepared to not only weather the storm but to one day (soon, hopefully!) emerge from these troubled waters ready to launch ahead when the waters calm. Much of its success—now and later—hinges on the successful implementation of automated sheet-handling equipment installed on three of its CNC turret punch presses (from Murata Machinery USA, Charlotte, NC) that allows lights-out fabrication.

Exponential Growth Spanning Four Decades

At one time, the contract manufacturer—with an equipment list that includes seven stamping presses, six CNC turret presses, four laser-cutting machines, 10 CNC press brakes and four robotic arc-welding cells—employed 115 working three shifts. Today, its 65 employees work one shift to manage projects from prototype development through production for customers in markets including commercial refrigeration (its largest customer base, at around 25 percent of its business), office furniture and RVs.

Crowell also has been successful at getting his foot in the door of new markets, including medical-appliance and military-vehicle fabrication. “Doors opened to allow our successful entry into these markets that are somewhat limited today but offer great potential in the near future,” he says, “thanks to our ability to work upfront with customers during the product-design stage.”

Capital Investments to Anticipate Rather than React

Before enduring the downturn that began late in 2008 for his company, Crowell managed his business through year after year of growth—some years 5 percent, other years 20 percent—all the while focused on anticipating the need for new equipment to keep up with the needs of its customers. Along that line—anticipate rather than react—two years ago he purchased a new Murata servo-electric CNC turret punch press to replace an aging hydraulic model. Its capabilities, combined with existing turret presses—three with automation that allows the firm to run lights out over an unmanned second shift—provide enough parts for downstream operations to alleviate any production bottlenecks.

We have more capacity in our press-brake area than in any other area of the shop,” Crowell says, “so we needed to run some of our turret presses more than just 8 hr. a day to smooth out our process and minimize lead times to our customers.”

American Metal Fab’s sweet spot has typically been mild-steel sheet 11 gauge and thinner, mostly focused on 18- to 24-gauge sheet. It has typically purchased a lot of special-sized blanks, says Crowell, but now works harder to combine blank orders into common blank sizes, where there are minimal differences in dimensions. This practice simplifies inventory tracking and means fewer and larger orders.

Always on the Prowl for Efficiency Gains

For four of its larger customers, the company monitors MRPs online two to three times a week. It might build 50 of one part, and as many as 500 of another.

For the commercial refrigeration industry, the firm fabricates refrigerator wrappers that require turret-press fabrication and then press-brake forming of primarily two basic blank sizes, one blank slightly smaller than the other.

“We schedule the two different sizes of wrappers back to back,” says Jason Crowell, John’s son and the firm’s vice president. “We developed a common turret setup for both jobs. Optimizing the tooling setup to handle both jobs eliminated a setup.”

Larger full-sheet parts such as the refrigerator-wrapper blanks prove ideal for producing lights-out on the Murata CNC turret presses, as do sheets with just two or three nested parts. “The more parts you nest into a sheet that runs unmanned,” says Jason, “the more chance something might break loose from the sheet and cause the press to shut down.” Blanks that run overnight get stacked by the automation equipment and operators separate parts from the blanks during the day.

The newest turret press in the American Metal Fab stable (a Motorum model 2548) can process sheets to 98.5 in. long and 49 in. wide, a significant upgrade from the other turret presses—all hydraulic models—in the stable. “Our other presses require repositioning for any work longer than 77 in.,” says Jason. The ability to run larger blanks on the new press without repositioning eliminates the unclamp-reposition-clamp cycle as well as the need to run through the entire tool setup a second time to finish a sheet. Running the larger sheets without repositioning has decreased cycle times by as much as 30 percent.”

Increased Laser Capacity, and a Commitment to Training

In addition to recent investments in new turret-press and automation technology, the Crowells purchased, in 2008, a new 5-kW laser-cutting machine. “We’re looking to

American Metal Fab produces these large blanks for refrigerator wrappers
American Metal Fab produces these large blanks for refrigerator wrappers on its CNC turret presses, then ships them flat for assembly in Mexico. Note the special engineered perforation pattern that allows the blanks to be folded during assembly—the series of slots and small holes optimizes material flow to improve fitup accuracy and repeatability in the corners.
increase sheet-thickness capacity,” says John, discussing the upgrade from his previous 2500-W laser-cutting capacity. “We can cut steel plate to 1 in. thick, which proves particularly useful when bidding on products for the military-vehicle market.”

“The new machine also can handle blanks to 6 by 12 ft.,” John adds, “allowing us to run longer parts compared to our previous 5 by 10-ft. capacity on our older laser-cutting machines.”

“We’ve also discovered that while nitrogen is required as the assist gas when cutting thicker sheet and plate,” adds Jason, “heavier than 12 gauge, for thinner work we can cut with shop air. Shop air also does a great job when etching with the laser.”

Our plant tour also led us past a lineup of CNC press brakes and robotic arc-welding cells, with operators moving from one area of the shop to another to tackle work wherever it needed doing. “I’m a big believer in cross training our people,” says Jason.

Training has been a big success factor for the firm, in areas such as 5S, material flow and kanban. “We’ve changed the way we purchase materials and performed our setups,” Jason explains. “We videotaped our setup procedures and made spaghetti charts to trace our footsteps, and then found ways to improve our efficiency.”

Much of the training investment made by the Crowells was subsidized by grants acquired from the State of Michigan, thanks to diligence by the firm’s human-resources department. “We’ve received as much as $14,000/yr.,” says John, “which we apply to training programs primarily administered by the Michigan Works! Association.”

Michigan Works! is a public-private partnership for workforce development that offers training, on-site technical assistance and other services. American Metal Fab provided more than 1000 hr. of training to 30 of its employees during a 10-week period in 2008, “quite a competitive advantage,” adds John Crowell. MF

 

See also: Murata Machinery USA, Inc.

Related Enterprise Zones: Automation, Fabrication

 


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